The long term objective of this project is to investigate the regulation of FGF signaling in lacrimal gland development, which has important implications for understanding the etiology of diseased lacrimal gland in human. The lacrimal gland develops through a branching morphogenesis process primarily driven by FGF signaling. This application will focus on the regulatory mechanism of FGF expression in the periocular mesenchyme and the downstream mediators of Ras signaling in the lacrimal gland epithelium. We will examine the signaling crosstalk between Ras and PI3K pathways. We will also investigate the role of ETS family transcription factors activated by Ras-MAPK signaling in lacrimal gland development. Finally, we will develop mouse genetic models to test the hypothesis that neural crest development is critical for Fgf10 expression in lacrimal gland. By investigating the regulation of FGF signaling in murine lacrimal gland, this project will both contribute to medical research in treating human congenital eye diseases and advance our understanding of the mesenchymal-epithelial interaction paradigm.